There is a forklift including a hydraulic drive device called an HST (Hydro Static Transmission) mounted between an engine, which is a drive source, and drive wheels (for example, Patent Literature 1). In the HST, a variable displacement traveling hydraulic pump driven by an engine and a variable displacement hydraulic motor driven by operating oil discharged from the traveling hydraulic pump are provided to a main hydraulic circuit that is a closed circuit. The HST allows a vehicle to travel by transmitting driving force of the hydraulic motor to the drive wheels.